Electric translation circuits



Feb. 5, 1935. M. E. BlVEN 1,990,366

ELECTRIC TRANSLATION CIRCUITS Filed Jan. 9, 1931 L I A 10 lnventqr.

MaUTlCe El. Blvens,

His Attorney.

Patented Feb. 5, I935 current: STATES? FAJZENZ'F OFFICEMETRIC-TRANSLATION Mam-ice -'E- BIvens,-'- S'otia, N5 Y assiiuor to Genmm, aflcvtporation olNe'w- Application Januaryfili 1931;" Serial No.507,748 lziomnm (onus- 368):

My inventionv relates to electric translation tive VMHG'iO! veryslightly positive potential durcircuitsandr more wparticularlyitmsuchcircuitsingsalternate half-cycles to *render' the valves involvingtheuse of electricnvailves.-. conducting alternately; However, shouldthe In many-translation circuits'utiliaingwlectrim negativegrid-potential of oneofthe valves devalves,='.such, fonexamphr, asthose: axlapiied2to rivedwfrom the-independent source be reduced 5convert direct current into alternating current; to-such awval ueasto'allow that valve to beit is absolutely. imporativewforsatisfactory, op,-- conw'conductive while theother-is still passingeration of the apparatus that notmorethanone: current; the-current=flowingwinthe-secondvalve of the'electric'valves should I beconductive-atinduces-such a=-potential=inthe secondary windany giveninstantl. For "example; in=the case of: ingassociatedwiththe-grid-circuit of the'first 10 sucha cncuit' 'irmludingelectricvvalves for con value as to-impress anegative potential uponvertingirdirectcin'rent into:alternating?current, the gridhotthis-valveand-thus positively hold known .in -theart aswanrinverter,,the=- conduc it-non-conducting. tivity of theivalvesvis controlledbythelpoten For a better understanding: of my invention l5vtials-of-theircontrol gridsrwhichnare oitemexa togetherwithotherand--furtherobjects there-- 5 cited from an independent-source ofaltematingz of" reference is -had to-the followingudeseription current:In the case: of abnormabconditionsv taken-1111f connection with theaccompanying in" this alternating currentfi exeitingw circuit; drawing.-and its scope will'be pointedout in the it sometimes oocum'thatzappositive potentiatis appendedclaims: The singiefigure of theacimpressed upon the -control:grichofone ofthecompanying'drawingisadiagrammatic represen- 2 valves-at an improper point in the cycle of:op'-- tationof one embodiment of-my invention as aperationof: theapparatusrwhilei'the-other valvepliad to -an-electricpower convertingapparaisstill conductingtcurrent; I tuswknewn in the-artasa seriesinverter.

It is-an object ofimy. inventiom-to provide-an Referringenow-to thedrawing, I have illusimprovedelectric translation including-:- trated anapparatusior receiving energy from the 25 electric :valves-whichwillobviate the' above mn direct current' circuit-:10, convertingit-into a1-tioned disadvantages of: the of: ternating current, and deliveringitto-the load the prior art and which shall be simple and re--circuit-11. This-apparatus comprises a-capaciliable in operation. tor-12 and awcircuit forcharging the capacitor It is -a -furtherobject-ofvmyrinvention to pro fromwthe source comprising- -anelectricvalve-13, 0 vide an? improvedrelectric;translationicircuit in-wthe-upperhalf of an inductive windingli-the-pricluding avpairot-electric -valves in which it -is maryw-inding of-transformer 25;and-the priimpossiblerfor one valve torbe rendered conductmary:winding1-15 of atransformer 16,- the'secing' due-to-abn0nnai--conditions of-the:excita ondaryiwindingti'l of which isconnected -to the tion'circuit-asvlong-ias cun'entisfiowingdrrtheloadcircuitdl. The capacitor 12-is also pro- 35 other valve; vided: witha discharge circuit comprising the In'accordancewith my inventionflIproviide a: lowerhalfsloftheinductive winding 14,- an electric" pair ofgrid? circuits for the-two eleetric valves;valve-l8;theprimary-winding-lSand the primary eaohcontainingthe-secondary-windmgiof a-gritk winding of transformer 25;Electric-valves 13ancl 40 transformerwhich'riyshunted' by:avunilateraliyi- 18-are each'providedwithan-anode,*a cathode and 40conductive devicesoeormected that-positive half a control grid and maybeof any of-theseveral cycles of the grid-potential arershunteclwfromtypes well known in the-a-rt; although" I prefer the grid :of the valve:Connectedin series-with toruse valves of the vaporelectric dischargetypeeach' of thesengridcircuitsis a secondaryrwind innwhichthe starting of 3current -inthe valve- 45. ing of a second transformer which :isenergizeck is determined-bytthepotential on its-control-grid 5 fromthealternating current 1 circuit 'oi tho 'apbut-in which the currentthrough the I valve may paratus-so that thei -polarity the-:secondary:beinterrupted only-'by-reduoingits'anode poten potential-is.-'.-dependei1t upon: whichvaive is con tiakbelow-thexcriticat:value:These valves prefduotingr Connectedimserieswith eaohhofvthcse erablyaJsohave-amegative grid potential charsecondaryt-windings is a-unilateralhh conductive aote ristic that is wcurrent may-be startedinthedevice so connected-.thahthe positivemalt-cycles valveby reducing-thenegative :grid potential to oftthe potentials-ofthis-transformeramheldsome small value- This-power converting: apback fromthwgridcircuitlWith thisarramge paratus together! with; a conventional arrangement; thegnidpotenfiel -of-ea.oh.=o-the electric mentfor: periodically andalternatelyrender- Ii valves norxnallylreacheaexsufiiciiently.en'lelliiegaing-thova1-es-13- and l8-conduoting isdescribed and claimed inUnited States Letters Patent No. 1,752,247 granted March 25, 1930, uponan application of Alan S. Fitz Gerald, and forms no part of the presentinvention. In order to insure that neither valve may be renderedconducting while the other valve is passing current, I have provided animproved excitation circuit for electric valves 13 and 18. The gridcircuitof theelectric valve 13 includes a current limiting resistor 19,the secondary winding 20 of a grid transformer 21,

a negative bias battery 22, a uni-laterally conductive device 23 and thesecondary winding 24 of a transformer 25. The primary winding of thetransformer 21 is energized from any suitable source of alternatingpotential of a frequency equal to that which it is desired to deliver tothe receiving circuit 11. The primary winding of the transformer 25 isconnected in series with the primary winding of the output transformer16. A uni-laterally conductive device 26 is connected across thesecondary winding of the transformer 21 and the negative bias battery22. This device virtually short circuits any positive half-cycles ofalternating potential and insures that only a negative potential will beapplied to the grid of the electric valve 13 from the transformer 21 Ifdesired, a current limiting resistor 27 may be included in the circuitof the secondary winding 20 in order to limit the current in the circuitduring those half-cycles in which the device 26 is conducting. It alsomay be found desirable to connect a resistor 28 across the secondarywinding 24 of the transformer and the uni-laterally conductive device23. A similar grid circuit is provided for electric valve 18 includingcurrent limiting resistors-29 and 30, the secondary winding 31 of thetransformer 21, a negative bias battery 32, a uni-laterally conductivedevice 33, and the secondary Winding 34'of the transformer 25. As in thecase of the grid circuit of valve 13, a uni-laterally conductive deviceis connected across the resistor. 30,'the secondary winding 31, and thebattery 32 and a resistor 36 is connected across the secondary winding34 and the device 33.

In explaining the operation of the above described apparatus it'will beassumed that the conditions of the exciting circuit of the gridtransformer 21 are initially normal so thata sine wave of alternatingpotential is supplied to the secondary windings '20 and 31. With thiscondition, the electric valves 13 and 18 are alternately renderedconductive, the capacitor 12 be-' coming charged from the source 10while thevalve 13 is conducting and discharging through the valve18'while it is conducting, thus delivering an alternating current to thereceiving circuit 11 as is well understood by those skilled in the art,or as is explained more fully in the above mentioned patent. Thefunction of the unilaterally conductive devices 26 and 35 connectedacross the secondary windings 20 and 31'respectively is to prevent apositive potential from being supplied to the grids of electric valves13 and 18, but, since these valves have negative grid potentialcharacteristics, they will be rendered conductive during theirrespective positive halfcycles of grid potential when their gridpotentials are substantially zero. If now, due to a transient effect orsome other cause, the polarity of the grid potential applied to thetransformer 21 should be reversed while the valve 13 is conducting, thenegative potential applied to the grid of the valve 18 would be zero,that valve would become conductive, and a virtual short'cir upon whichof the valves 13 and 18 is conducting.

Each of the grid circuits of the valves 13 and 18 includes a potentialderived from this grid transformer 25 which is so'connected that anegative potential is impressed upon the grid of one of the valveswhenever the other valve is conducting current. Under the assumedconditions, as the grid potential reverses polarity while the electricvvalve 131 is conducting, the secondary winding 31 of the transformer 21will tend to impress a positive potential upon the grid of electricvalve 18. However, the uni-laterally conductive device 35 is soconnected asto pass currentin this direction 'so that substantially thewhole potential of the winding 31 is consumed in the resistor'30 and'thepotential impressed'upon the grid of the valve 18 from the winding 31will be substantially zero. At the same time, the current flowing inelectric valve 13 flows through the primary winding of the gridtransformer 25 in such a direction as to induce a potential in thewinding 34 which 'impressesa negative potential on the grid of the valve18, thus positively preventing this valve from becoming conducting aslong as the valve 13 is conducting current. In order to prevent thesecondary windings 24 and 34 of the transformer 25 from impressingpositive potentials upon the grids of the valves 13 and 18 which wouldinterfere with the normal operation of the apparatus, theuni-laterally'conductive devices 23 and 33 respectively, have beenconnected inserieswith these windings to interrupt the positive halfcycles induced in them. In addi tion, the resistors 28 and 36-have beenconnected I across the secondary windings 24 and 34, respectively, inorder that this circuit may not interfere with the normal operation ofthe main grid exciting circuits.

While I have stated above that the electric valves 13 and 18 preferablyhave negative grid potentialcharacteristics, it will be obvious to thoseskilled in the art that valves having positive grid potentialcharacteristics may be used by-including a small resistance in serieswith the uni-laterally conductive devices-26 and 35 in the grid circuitsso that a small portion of the positive half-cycles of the windings 20and 31 may be impressed upon the grids of the valves 13 and 18respectively. Also, it will be obvious that the primary winding of thetransformer 25 may be connected to any other portion of the alternatingcurrent circuit which will give an.

indication as to which of the valves 13 and 18 is conducting current,all without departing from my invention.

' While I have described what I at present consider the preferredembodiment of my invention it'will be obvious to those skilled in theart that various changes and modifications may be made without departingfrom my invention and I, therefore, aim in the appended claims to coverall such changes and modifications as fall within the true spirit andscope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In combination, an electric translation circuit including a pluralityof electric valves, means for normally controlling the conductivity ofsaid valves, and means responsive to the conductivity of certain of saidvalves for rendering ineffective abnormal conditions in the conductivitycontrolling means of the other valves.

2. In combination, an electric power converting apparatus including aplurality of electric valves, means for normally controlling theconductivity of said valves, and means responsive to the flow of currentin one of said valves for rendering ineffective abnormal conditions inthe conductivity controlling means with respect to another of saidvalves.

3. In combination, an electric power converting apparatus including apair of electric valves each provided with a control grid, means forexciting said control grids to render said valves alternatelyconductive, and means responsive to the flow of current in one of saidvalves for rendering, inefiective abnormal conditions in said excitingmeans with respect to the other valve.

4. In combination, an electric power converting apparatus including apair of electric valves each provided with a control grid, a gridcircuit for each of said valves including a source of alternatingpotential for exciting said grids and means for substantially shuntingthe positive half cycles of said potentials from said grids, and meansresponsive to the flow of current in one of said valves for renderingsaid exciting means ineffective to render the other valve conductive.

5. In combination, an electric power converting apparatus including apair of electric valves each provided with a control grid and a gridcircuit for each of said valves including a source of alternatingpotential, means for substantially shunting the positive half cycles ofsaid potentials from said grids, and means for impressing a negativebias upon either of said grids when the other valve is conductive.

6. In combination, an electric, power converting apparatus including apair of electric valves each provided with a cathode, an anode and acontrol grid, a grid transformer provided with a pair of secondarywindings, a grid circuit for each of said valves including one of saidsecondary windings and a unilaterally conductive device connected inparallel thereto, and means for impressing a negative bias upon eitherof said grids when the other valve is conductive.

7. In combination, an electric power converting apparatus including apair of electric valves each provided with a control grid, means forexciting said control grids to render said valves alternatelyconductive, a grid transformer having a primary winding energized fromthe alternating current circuit of said apparatus, and a pair ofsecondary windings, each connected to the grid of one of said valves,and a unilaterally conductive device in each of said grid connectionswhereby a negative bias potential is impressed upon the grid of eithervalve whenever the other valve is conducting.

8. In combination, an electric power converting apparatus including apair of electric valves each provided with a control grid, grid circuitsfor exciting said control grids to render said valves alternatelyconductive, a grid transformer having a primary winding energized fromthe alternating current circuit of said apparatus and a pair ofsecondary windings, and a resistor and a unilaterally conductive deviceconnected in circuit with each of said secondary windings, each of saidresistors being included also in one of said grid circuits.

9. In combination, a source of direct current, a pair of electric valveseach provided with an anode, a cathode, and a control grid, a capacitor,a circuit for charging said capacitor from said source including one ofsaid valves, a circuit for discharging said capacitor including theother of said valves, means for normally rendering said valvesalternately conductive, and means responsive to the flow of current inone of said valves to prevent the other valve from becoming conductivedue to abnormal conditions in said conductivity controlling means.

10. In combination, anelectric valve provided with an anode, a cathode,and a control grid, a grid circuit connecting said grid and cathode andincluding a source of alternating potential, a unilaterally conductivedevice connected in parallel to said source to shunt half cycles of saidpotential of a predetermined polarity from said grid, and means includedin said control circuit for maintaining said valve nonconductive underpredetermined circuit conditions comprising a source of alternatingcurrent potentials variable in accordance with said conditions.

11. An electric translating circuit including an electric valve providedwith an anode, a cathode, and a control electrode, a control circuit forsaid control electrode including a source of potential for renderingsaid valve conductive, and means for maintaining said valvenonconductive under predetermined circuit conditions comprising a sourceof alternating potential variable in accordance with said circuitconditions and included in said control circuit, and means forsuppressing the positive half cycles of said alternating potential fromsaid grid.

12. An electric translating circuit including an electric valve providedwith an anode, a cathode, and a control electrode, a control circuit forsaid control electrode including a source of periodic potential forperiodically rendering said valve conductive, and means for maintainingsaid valve nonconductive under predetermined circuit conditionscomprising a source of alternating potential variable in accordance withsaid circuit conditions and included in said control circuit, andrectifier means connected in circuit with said source of alternatingpotential for suppressing the positive half cycles of said alternatingpotential from said grid.

MAURICE E. BIVENS.

